The Model Of Deforming Mode Tube Under Axial Loading

(1)

THE MODEL OF DEFORMING MODE TUBE UNDER AXIAL LOADING

MUHAMAD SYAFIQ BIN ABDUL WAHAB

(2)

THE MODEL OF DEFORMING MODE TUBE UNDER AXIAL LOADING

MUHAMAD SYAFIQ BIN ABDUL WAHAB

A report submitted

in fulfilment of the requirements for the degree of

Bachelor of Mechanical Engineering (Structure & Materials)

Faculty of Mechanical Engineering

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

(3)

i APPROVAL

I hereby declare that I have read this project report and in my opinion this report is sufficient in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering (Structure & Materials).

Signature : ………….………

Supervisor’s Name : PROF. DR. MD. RADZAI BIN SAID

(4)

ii DECLARATION

I declare that this project report entitled “The model of deforming mode tube under axial loading” is the result of my own work except as cited in the references.

Signature : ………...

Name : MUHAMAD SYAFIQ BIN ABDUL WAHAB

(5)

iii DEDICATION

(6)

iv

ACKNOWLEDGEMENTS

Alhamdulillah, all praises to Allah for the strengths and His blessing in completing this search. To the great prophet Muhammad (Allah peace be upon him) a prophet of mercy and the light of the Worlds.

Firstly, I would like to sincerely thank my supervisor Prof. Dr. Md Radzai Bin Said for his guidance, advices and support. Without his valuable assistance, this work would not has been completed. I am also indebted to my friends for their contributions. I takes this opportunity also to thank the Faculty of Mechanical Engineering’s laboratory management for their cooperation especially to the technicians during performing experimental works at the laboratory.

Most importantly, I am forever grateful my family who understands the importance of this work, none of this would have been possible without their patience and help.

(7)

v ABSTRACT

(8)

vi

ABSTRAK

Tiub berdinding nipis merupakan salah satu struktur menyerap tenaga yang telah digunakan untuk menyebarkan tenaga dan meningkatkan kecekapan kebolehtahanan hentakan. Semasa kemalangan berlaku, tiub berdinding nipis menyerap tenaga kinetik dan menukar kepada bentuk tenaga lain. Oleh itu, struktur menyerap tenaga ini memberikan penyerapan tenaga yang mencukupi sebelum memukul manusia. Kajian ini adalah untuk mengkaji tiub aluminium persegi dan tiub PVC bulat yang tertakluk kepada beban statik kuasi dengan menggunakan mesin mampatan universal atau mesin Instron. Mod perubahan bagi kedua-dua tiub diperhatikan. Model kertas dibentuk dengan menggunakan kertas tebal untuk menggambarkan cara perubahan bagi tiub aluminium persegi sahaja. Ujian tegangan dijalankan bagi kedua-dua tiub untuk mendapatkan sifat-sifat mekanik tiub. Terdapat tiga perbezaan panjang untuk setiap jenis tiub telah diuji di bawah beban statik kuasi. Keputusan eksperimen yang diperolehi daripada ujian telah dibandingkan dengan keputusan teori yang diperolehi daripada persamaan matematik. Dari perbandingan, satu persetujuan yang baik telah dicapai di antara keputusan teori dan ujikaji. Analisis terhadap graf jarak beban termasuk keputusan beban puncak, purata beban, penyerapan tenaga dan plastik lipatan. Lipatan plastik untuk tiub PVC adalah lebih besar daripada tiub aluminium kerana sifat kekenyalannya. Hasil daripada ujian, tiub PVC bulat dan aluminium persegi tiub berubah dalam mod diamond untuk ketiga-tiga perbezaan panjang. Siri model kertas dibentuk untuk pelbagai peringkat proses perubahan untuk menggambarkan fenomena proses pemampatan tiub aluminium persegi berlaku semasa ujian. Kesimpulannya, keputusan yang diperoleh daripada kajian ini seperti siri model kertas perubahan bentuk tiub aluminium segi empat sama akan digunakan sebagai alat bantu pembelajaran yang baru untuk meningkatkan kefahaman tentang fenomena ujian mampatan.

(9)

vii

TABLE OF CONTENTS

PAGE APPROVAL DECLARATION DEDICATION ACKNOWLEDGEMENTS ABSTRACT ABSTRAK

TABLE OF CONTENT LIST OF TABLES LIST OF FIGURES

LIST OF ABBREVIATIONS

LIST OF SYMBOLS

i ii iii iv v vi vii x xi xiv xv CHAPTER

1 INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 3

1.3 Objective 3

1.4 Scope Of Project 3

2 LITERATURE REVIEW 4

2.1 Introduction 4

2.2 Energy Absorption 5

2.2.1 Collapse Modes 5

2.3 Quasi-Static Test 7

2.3.1 Axial Loading on Circular Polyvinylchloride (PVC) 8

2.3.2 Axial Loading on Square Aluminium 10

(10)

viii

2.5 Paper Models of Deformation Modes 12

2.6 Low Speed Camera 14

3 METHODOLOGY 15

3.1 Introduction 15

3.2 Flow Chart for Tensile Test 16

3.3 Material Selection for Tensile Test 17

3.4 Material Preparation for Tensile Test 16

3.4.1 Engineering Drawing for Tensile Test 19

3.4.2 Cutting Process of Tensile Test Specimen 20

3.4.3 Fabrication of Tensile Test Specimen 21

3.5 Tensile Testing 22

3.6 Flow Chart for Quasi Static Testing 23

3.7 Material Selection For Quasi Static Testing 24

3.8 Material Preparation for Quasi Static Testing 25

3.9 Experimental Setup for Quasi Static Testing 27

3.10 Develop a Paper Model Using Thick Paper 28

4 RESULT AND ANALYSIS 30

4.1 Introduction 30

4.2 Tensile Test 31

4.2.1 Graph Tensile Stress Against Tensile Strain 31

4.2.2 Experimental Tensile Testing Result 33

4.3 Type of Deforming Modes for Aluminium and PVC Tubes under Quasi Static Test

34

4.3.1 Deforming Modes for Aluminium Tubes under Quasi Static Test

34

4.3.2 Deforming Modes for PVC Tubes under Quasi Static Test

36

4.4 Quasi Static Test Result 37

4.4.1 Square Aluminium Tube with Length 100mm 37

4.4.1.1 Comparison Between Experimental and Theoretical Value for Aluminium Tube

(11)

ix with Length 100mm

4.4.2.1 Comparison Between Experimental and Theoretical Value for Aluminium Tube with Length 150mm

43

4.4.3.1 Comparison Between Experimental and Theoretical Value for Aluminium Tube with Length 200mm

48

4.4.4 Sample Calculation for Square Aluminium Tubes

50

4.4.5 Circular PVC Tube with Length 100mm 52

4.4.5.1 Comparison Between Experimental and Theoretical Value for PVC Tube with Length 100mm

54

58

63

4.4.8 Sample Calculation for Circular PVC Tubes 65

4.5 Paper Model For Square Aluminium Tube 67

5 CONCLUSION AND RECOMMENDATION 69

5.1 Introduction 69

5.2 Conclusion 69

5.3 Recommendation 70

REFERENCES 71

(12)

x

LIST OF TABLES

TABLE TITLE PAGE

2.1 Collapse modes under axial loading 5

4.1 Experimental tensile testing result for aluminium 33

4.2 Experimental tensile testing result for PVC 33

4.3 Time taken for the tubes to compressed 60% from their total length 35

4.4 Comparison between experimental and theoretical results of

quasi-static testing for aluminium tube with length 100mm

40

44

49

4.7 Properties of square aluminium tubes 50

quasi-static testing for PVC tube with length 100mm

55

quasi-static testing for PVC tube with length 150mm

59

4.10 Comparison between experimental and theoretical results of quasi-static testing for PVC tube with length 200mm

64

(13)

xi

LIST OF FIGURES

FIGURE TITLE PAGE

2.1 Force displacement curve for collapse mode 6

2.2 INSTRON 5585 testing machine 8

2.3 PVC tubes on testing machine 9

2.4 Local buckling at the upper part of the tubes 9

2.5 Collapse modes for aluminium square tubes 10

2.6 Euler buckling deforming mode 11

2.7 Theoretical model of a collapsing tube showing details of travelling

hinge

12

2.8 Series of collapse mode and paper models 13

2.9 Paper models of different in length 13

2.10 Low speed digital video camera 14

3.1 Schematic representation of general experimental setup 15

3.2 Flow chart of the testing 16

3.3 Aluminium square tubes 17

3.4 Polyvinylchloride (PVC) tubes 17

3.5 Dimension of tensile test specimen for aluminium (ASTM E8) 18

3.6 Dimension of tensile test specimen for PVC (ASTM D638) 19

3.7 Drawing of tensile test specimen for aluminium 19

3.8 Drawing of tensile test specimen for PVC 20

3.9 Laser cutting machine 20

3.10 Tensile test specimen for PVC and aluminium 21

3.11 INSTRON 8872 testing machine and set up for tensile testing 22

3.12 Flow chart for quasi static testing 23

(14)

xii

3.14 PVC circular tubes 24

3.15 Bandsaw machine 25

3.16 Cutting process for aluminium tubes 26

3.17 Cutting process for PVC tubes 26

3.18 Three difference of height for aluminium and PVC tubes 26

3.19 Experimental set up for quasi static testing 27

3.20 Manila paper 28

3.21 The lines of folding and point of plastic hinges 29

4.1 Tensile test specimens break (aluminium and PVC) 31

4.2 Graph of tensile stress against tensile strain for aluminium 32

4.3 Graph of tensile stress against tensile strain for PVC 32

4.4 Aluminium tubes with three different length (100mm, 150mm,

200mm)

34

4.5 PVC tubes with three different length (100mm, 150mm, 200mm) 36

4.6 Sample 1 of load displacement curve for the aluminium tube with

length 100mm

37

4.7 Sample 1 of deforming mode for aluminium tube with length 100mm 38

length 150mm

41

length 200mm

45

4.12 Sample 1 of load displacement curve for PVC tube with length

100mm

52

4.13 Sample 1 of deforming mode for PVC tube with length 100mm 53

150mm

56

4.15 Sample 1 of deforming mode for PVC tube with length 150mm 57

4.16 Global buckling for sample 2 with length 200mm 60

200mm

61

(15)

xiii

4.19 Top view of tube and paper model 67

(16)

xiv

LIST OF ABBEREVATIONS

IEA - Impact Energy Absorption

PVC - Polyvinylchloride

(17)

xv

LIST OF SYMBOLS

Pcr - Critical Buckling Load

Pm - Mean Load

E - Young’s Modulus / Energy Absorb

σu - Tensile stress at yield

I - Moment of Inertia

L - Length of Tubes

S - Deformation

Hm - Half plastic folding

t - Thickness

v - Poisson Ratio

OD / d - Outer Diameter

mm - Millimetre

w - Width

LO - Overall Length

WO - Overall Width

GPa - Giga Pascal

(18)

1 CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

(19)

2

Polyvinylchloride (PVC) and aluminium are most popular material that are suitable in making the IEA device. This is because the material provide significant benefit such has high strength and durability, lightweight materials and lower in cost of processing or machining process. PVC was introduced in industry on 1832 and the first PVC pipes and tubes were produced on 1932 using a roll mild and hydraulic extruder (Pled et al., 2007). While, the first aluminium was produced in 1885 that containing iron and copper (Sheasby & Pinner, 2001). Too many application using this material due to low density and high mechanical strength.

One of the testing to deform the PVC and aluminium tubes is by using quasi-static testing (Ahmad, 2009). In this testing, the tubes are compressed at a constant rate using conventional tensional testing machine (INSTRON 8802). Tubes are compressed at a very slow constant speed in range of 0.0015 m/s up to 0.1 m/s. The height of the collapse modes of the tubes depend on the long of the tube before testing (Meng et al., 1983).

(20)

3 1.2 PROBLEM STATEMENT

One of the objective of this topic is expose to the students on how the deforming modes occurred on the tubes after undergoes an impact test. Nowadays, additional tools is needed to understand on how the phenomena of the deforming mode of the tubes occurred during the testing. So, study and research about the properties of PVC and aluminium is needed in identifying the behaviour of deforming modes for both materials. Then, modelling the results of the deforming mode for square aluminium tubes only by using thick paper which it can be used as a teaching and learning purpose. The series of paper model is developed for presentation in order to increase the understanding of students on phenomenon occurred during compression test is various stages.

1.3 OBJECTIVE

The objectives of this project are as follows:

1. To perform and observe the deforming mode of PVC and aluminium tubes with

different length under quasi-static loading.

2. To model the deforming mode of the square aluminium tube only by using a thick

paper.

1.4 SCOPE OF PROJECT

The scopes of this project are:

1. Carry out a preliminary study and review past research on the scope of study

about quasi-static loading and deforming modes which is based on standard.

2. Perform a quasi-static loading on PVC and aluminium tubes and observe their

deforming mode.

3. Result of deforming mode for square aluminium tube only are modelling by

(21)

4 CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

This chapter study about the paper model of the square aluminium tubes under quasi-static loading testing, axial loading on both types of materials used (aluminium and polyvinyl chloride, PVC) and high speed digital camera to capture the impact event.

(22)

5 2.2 ENERGY ABSORPTION

Energy absorption means that the required energy to cause the collapse of the structures or tubes under the impact loading (Andrews et al., 1983). The energy firstly transformed into elastic strain energy in the deformed tubes and the remainder of the energy is dissipated in plastic deformation on the tubes during collapse occurred (Alghamdi, 2001). There are seven types of collapse modes on tubes that has been identified which are concertina, axisymmetric concertina, diamond, concertina/diamond, Euler, tilting of tube axis and 2-lobe diamond (Albert et al., 2016).

2.2.1 COLLAPSE MODES

[image:22.595.139.526.440.743.2]

Results from the axial loading to the test tubes produced seven types of collapse modes which is (Andrews et al., 1983):

Table 2. 1: Collapse modes under axial loading

Collapse modes Description

Concertina At one end of the tube where starting point of axisymmetric

and sequential folding. Axisymmetric

concertina

Simultaneous type of collapse will occurred along the length of the tubes.

Diamond Change in the cross section shape of the tubes affected by

the sequential folding.

Concertina /

Diamond

Folding first occurred in concertina mode and changing to diamond mode.

Euler Tubes bending during the testing.

Tilting of tube axis

Shearing occurred on the tubes with platen surface at the one end.

(23)

6

[image:23.595.159.476.174.399.2]

There are four different regions in the force-displacement curve for the collapse mode as shown in the Figure 2.1 which is the post-buckling stage, elastic stage, the crippling stage and the collapse stage.

Figure 2. 1: Force displacement curve for collapse mode (Source : Junning Sun, 2000)

(24)

7 2.3 QUASI-STATIC TEST

The quasi-static test was carried out by using INSTRON 5585 testing machine (accuracy ± 1% of applied load) as shown in Figure 2.2. The plate at the lower part of the machine was fixed and not move (Trondheim, 2005). To ensure uniform load distribution of the test specimens, the load was applied through a rigid steel plate that connected to the hydraulic actuator. The friction between the rigid steel plate and the upper end surface of the test specimens is very important to prevent from any movement during the testing process. The axial load was applied at a constant speed during the testing which the speed in a range of 1.5 x 10-3_{m/s to 0.1 m/s. The actual crush condition didn't be able represent by doing this} quasi-static tests because during the crush, the structures of the tubes will dissipate energy over the entire period until the tubes are completely collapses. It means that the speed of the tests is one of the major factor influences on the capability of energy absorption. So, materials selection under the quasi-static tests are usually not represent the real performance of the structure in the event of a crash.

There are some advantages of the quasi-static tests (Junning Sun, 2000):

i. Lower maintenance and reduce the risk of damage on the crosshead of the tubes.

ii. Test’s equipment usually easy to conduct and operate.

iii. This test usually run to understand the different failure modes of the different

materials used based on the crush rate.

There are some disadvantages of the quasi-static test:

i. This quasi-static tests usually represent not an actual characteristic of the selected materials as a real performance of the structure in the event of a crash. This is because this test usually conducted to investigate the failure modes of the tubes.